1. Field of the Invention
This invention relates to an apparatus for dropping and filling liquefied inert gases wherein the liquefied inert gases are dropped and filled into a canning can immediately before rolling thereof to generate given pressure within the canning can after sealed.
2. Description of the Prior Art
Even in canning of drinks and food not containing carbon dioxide gas, it is desired that cans manufactured of a material having a thin wall-thickness similar to cans for drinks containing carbon dioxide gas are used as containers.
Therefore, attempts have been made wherein the liquefied inert gases are dropped and filled into a can immediately before rolling thereof to increase internal pressure after sealed, thus making up for the shortage of the strength of the can made of a thin material. However, the quantity of liquefied inert gases to be dropped and sealed varies with the temperature of material to be filled, the operating speed of the rolling device, the magnitude of the space in the upper portion within the can, etc.
The inert gas dropping device is provided with a storage tank for liquefied inert gases and a dropping nozzle, and in order to accurately control the aforesaid quantity of dropping, it is necessary to control the quantity of the liquefied gases to be supplemented into the storage tank.
The simplest way considered is that the storage tank for liquefied gases is interiorly provided with a float so that the float may be moved up and down to deviate the liquefied gas to cause fluctuation of internal pressure, by which change in said pressure the liquefied inert gases may flow into the storage tank from a liquefied gas cylinder.
However, it is difficult to always prevent the pressure within the storage tank from acting on the liquefied gas flowing downwardly from the dropping nozzle, and therefore, the quantity of dropping is difficult to to be controlled by the dropping device of the system as described.
The present inventor has proposed that in order to provide a precise control of the dropping quantity of liquefied gases, a storage tank is interiorly provided with a level gauge so that with the value detected thereby, the supplemented quantity of liquefied gases is controlled by means of an electromagnetic valve or the like, and on the other hand, with the regulation of pressure within the tank, main adjustment of the dropping quanity is finely made by the valve attached to the dropping nozzle.
This dropping device is precise in control of the dropping quantity but has a drawback in that the control device is complicated and expensive.